1. Field of the Invention
The present invention relates to motor assemblies. More specifically, the invention relates to motor assemblies for moving seats along seat tracks in vehicles.
2. Related Art
Various systems are known for adjusting the horizontal and vehicle position of seats in vehicles. Typically, DC brush-type motors drive lead screws using a gear box that is situated perpendicular to the lead screw. One end of the lead screw has a drive nut attached to the seat track mechanism, and the other end is contained in the gear box. The gear box is either attached to the motor or is connected to the motor by a flexible shaft.
This conventional arrangement allows high forces on the lead screw to be exerted on the gear box that is oriented perpendicular to the lead screw. These high forces reduce the operating life of the gear box and motor.
Furthermore, using flexible shafts between the motor and gear box generates noise, and frictional forces in the perpendicular gear boxes lead to undesirable "whinnying" sounds.
Thus, there is a need in the art to provide a movable seat track motor assembly in which forces transmitted along a rotatable lead screw are diverted from gear box elements leading to a motor, and in which uneven and undesirable motor sounds are eliminated.
Moreover, some conventional systems have "memory" arrangements for monitoring and remembering the position of the seat. Typically, a potentiometer has been linked to rotation of the lead screw through a gear box of typically 1200:1 gear ratio, so that measuring full travel of a drive nut on the lead screw would correspond to about 200 degrees of rotation of the potentiometer. This arrangement has increased the cost and complexity of measuring the position of a seat by measuring the position of a drive screw.
Therefore, there is a need in the art to provide an simple, cost-effective arrangement in which the position of the seat can be accurately monitored.
It is to fulfill these and other needs in the art that the present invention is directed.